JP2019049660A - Cam follower and lens barrel - Google Patents

Abstract

To provide a cam follower capable of effectively preventing backlash between a wall surface of a groove and itself from occurring even with a simple configuration, and a lens barrel.SOLUTION: A cam follower 200 includes: a cam follower body 210 engaging with at least one groove; a coil spring 220 held by a holding part 211 which is provided in a circumferential direction relative to a center axis of the cam follower body 210; and a pressing member 230 which protrudes from a hole provided in a side surface of the cam follower body 210, and which elastically contacts with one wall surface of the groove by energizing force of the coil spring 220.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cam follower capable of preventing generation of rattling of a moving member moved by a cam and a lens barrel having the same.

  In a lens barrel mounted on a single-lens reflex camera or the like, the movement of the lens holding frame that moves in response to zooming or focusing is mainly achieved by the cooperation of a cam groove (lead cam groove) and a rectilinear groove.

  A slight clearance is provided between the cam groove and the cam follower engaged therewith, which enables smooth driving. However, if backlash occurs between the cam groove and the cam follower due to this clearance, the positional accuracy of the lens to be held is lowered, which causes a problem that the optical performance is lowered. In addition, there arises a problem that the accuracy of zooming and focusing decreases. In addition, when driven by the operation of the photographer himself, the quality is lowered by the occurrence of rattling during the operation.

  In order to solve such a problem, various techniques for suppressing the backlash between the cam groove and the cam follower have been conventionally proposed.

  For example, in the invention disclosed in Patent Document 1, in a zoom lens barrel in which a lens is controlled to move by a cam member and a cam follower, a leaf spring pressing the cam follower against the cam surface of the cam member and a lens frame holding the lens And a fixing direction adjusting means for adjusting the fixing direction of the cam follower, and the pressure contact degree of the leaf spring can be adjusted by adjusting the fixing direction of the cam follower by the fixing direction adjusting means.

  According to the present invention, it is possible to obtain a smooth zoom operation while achieving both size reduction and cost reduction.

Patent 3482266

  However, the above-described prior art has the following problems. That is, in the invention disclosed in Patent Document 1, it is necessary to set the width of the cam groove to be equal to or larger than the diameter of the cam follower, so the strength of the cam cylinder may decrease or the lens barrel may be enlarged.

  In addition, when an impact is applied to the lens barrel due to a drop or the like, the impact force is concentrated on the plate spring, and as a result, the plate spring may be plastically deformed.

  Further, since the leaf spring can not be fixed to the cam follower, it can not be stored and managed in the incorporated unit state. Therefore, the number of assembling steps is increased.

  The present invention has been made in view of such a situation, and provides a cam follower capable of effectively preventing the occurrence of backlash with the groove wall surface while having a simple configuration, and a lens barrel having the same. The purpose is to

  In order to achieve the above object, a cam follower embodying the present invention comprises a cam follower main body engaged with at least one groove, and a coil spring held by a holding portion provided circumferentially with respect to a central axis of the cam follower main body And a pressing member that protrudes from the hole provided on the side surface of the cam follower main body and that elastically contacts one of the wall surfaces of the groove by the biasing force of the coil spring.

  In the cam follower according to the present invention, preferably, the pressing member has a projecting portion projecting through the hole and a spring receiving portion in pressing contact with both ends of the coil spring, and the pressing member uses the coil spring as the holding portion. Among the biasing forces generated in the spring receiving portion by the elastic compression, the resultant force in the projecting direction of the projecting portion is the biasing force of the pressing member.

  In the cam follower according to the present invention, preferably, an urging mechanism including a coil spring and a pressing member in the central axis direction is engaged with the two groove portions adjacent in the central axis direction and corresponding to the respective groove portions. It features that it possesses lamination.

  According to the cam follower of the present invention and the lens barrel having the same, it is possible to effectively prevent the occurrence of backlash with the groove wall surface with a simple configuration.

  Furthermore, it becomes possible to easily manage and handle in a unit state in which the biasing mechanism is incorporated into the cam follower main body.

It is a fragmentary sectional view of lens barrel 100 which is one embodiment of the present invention. It is a figure for demonstrating the cam follower 200, (a) is a perspective view of the cam follower 200 and screw 240, (b) is sectional drawing of the cam follower 200. As shown in FIG. It is a schematic diagram for demonstrating generation | occurrence | production of urging | biasing force, (a) is sectional drawing for demonstrating the urging | biasing force which arises in the pressing member 230, (b) shows the relationship between the urging mechanism of the cam follower 200, and a cam groove. It is a top view for explaining. FIG. 7 is a cross-sectional view for describing a holding state of a coil spring 220. It is a perspective view of cam follower 200 which is a 2nd embodiment.

  Hereinafter, the best mode for carrying out the present invention will be described according to the attached drawings. The present invention is not limited by the embodiment.

  FIG. 1 is a partial cross-sectional view of a lens barrel 100 to which the present invention is applied. The lens barrel 100 shown in this figure is a single focus lens, and has at least a first lens group G1 and a second lens group G2 in order from an object side as an imaging optical system.

  The lens barrel 100 has, as main components, a fixed barrel 110, a cam barrel 120, a straight barrel 130, and a focus operation ring 140 in addition to the imaging optical system. The rectilinear barrel 130, the fixed barrel 110, the cam barrel 120, and the focus operation ring 140 are disposed in this order from the inner peripheral side with the optical axis of the imaging optical system as the center.

  The first lens group G1 and the second lens group G2 are advanced and retracted in the optical axis direction according to focusing. The upper side in the drawing shows the lens barrel 100 in the INF state, and the lower side shows the shortest photographing state. The lenses of the respective lens groups are fixed to the respective mirror chambers by caulking, a pressing ring or the like, and the respective mirror chambers are further fixed to the lens moving frame.

  The first group moving frame 151 holds the first lens group G1, and is fastened to the rectilinear barrel 130 by screws (not shown). The first group moving frame 151 is further engaged with the rectilinear guide groove 111 provided in the fixed cylinder 110 and the cam groove 121 provided in the cam cylinder 120 via a plurality of cam followers 200. Thus, the first group moving frame 151 is held at a predetermined position.

  On the other hand, the second lens group moving frame 152 holds the second lens group G2, and via a cam follower (not shown), a rectilinear guide groove (not shown) provided on the fixed barrel 110 and a not shown on the cam barrel 120. It is engaged with the illustrated cam groove.

  The fixed cylinder 110 and the cam cylinder 120 constitute a cam mechanism, and when the user operates the focus operation ring 140, the operation force is transmitted to the cam cylinder 120, and the cam cylinder 120 rotates around the optical axis. The cam follower 200 is advanced and retracted in the optical axis direction by the cooperation of the cam groove 121 and the rectilinear guide groove 111 by the rotation of the cam barrel 120. By setting the cam groove 121 to a predetermined shape, the first group moving frame 151 and the second group moving frame 152 are moved while satisfying a predetermined positional relationship, whereby the focusing operation of the lens barrel 100 is performed.

  FIG. 2 is a view for explaining a cam follower 200 embodying the present invention shown in FIG. 2A is a perspective view of the cam follower 200 and the screw 240, and FIG. 2B is a cross-sectional view of the cam follower 200. As shown in FIG. The biasing mechanism of the cam follower 200 will be described using these figures.

  As shown in the figure, the cam follower 200 has a cam follower main body 210, a coil spring 220 held in the cam follower main body 210, and a pressing member 230 protruding from the side surface of the cam follower main body 210. Further, the screw 240 is inserted into a through hole provided at the center of the cam follower main body 210. In the present embodiment, the cam follower 200 is fixed by fastening the inserted screw 240 with a screw hole provided in the first group moving frame 151.

  The outer peripheral portion of the cam follower main body 210 abuts on the rectilinear guide groove 111 of the fixed barrel 110 and the cam groove 121 of the cam barrel 120, and constitutes a side surface that slides. The cam follower 200 of this embodiment has two stages of sliding surfaces which engage with different grooves. In the present embodiment, the lower portion engages with the rectilinear guide groove 111 of the fixed barrel 110, and the upper portion engages with the cam groove 121 of the cam barrel 120.

  Next, the mechanism of the biasing mechanism provided in the cam follower 200 of the present invention will be described. As described above, the coil spring 220 and the pressing member 230 are held inside the cam follower main body 210.

  The coil spring 220 is held along the holding groove 211 provided on the inner peripheral side of the cam follower main body 210 as shown in FIG. Then, the pressing member 230 similarly located in the holding groove 211 is held by being elastically compressed the coil spring 220.

  The pressing member 230 is structured to have a projecting portion 231 protruding from a hole provided on the side surface of the cam follower main body 210 and a spring receiving portion 232 in pressing contact with the coil spring 220 held inside the cam follower main body 210. It can be said that the pressing member 230 has a Y-shape or a piercing shape as a whole.

  By urging the coil spring 220 elastically compressed against the spring receiving portion 232 of the pressing member 230, the projecting portion 231 protrudes from the side surface of the cam follower main body 210 and abuts on the wall surface of the cam groove 121 with which the cam follower 200 engages. Since the spring receiving portion 232 is always biased by the compressed coil spring 220, the contact of the projecting portion 231 is an elastic contact.

  FIG. 3A is a schematic view for explaining the magnitude and direction of the biasing force generated by the coil spring 220. FIG. As described above, the pressing member 230 is in contact with the coil spring 220 held in the circumferential direction at the spring receiving portion 232, and an urging force that causes the coil spring 220 in a compressed state to return to the natural length on the contact surface of both members. Has occurred.

  There are two spring receiving portions 232, and the biasing forces generated here have the same magnitude but different directions. The projecting portion 231 protrudes from the side surface of the cam follower main body 210 with the resultant force of the pressing member 230 which has received the two urging forces.

  The magnitude of the resultant force generated on the pressing member 230 is influenced by the direction of the biasing force generated between the coil spring 220 and the spring receiving portion 232. In principle, if the direction of these biasing forces matches the direction of the resultant force, the magnitude of the resultant force is the largest. That is, the length of the leg of the spring receiving portion 232 is extended along the holding groove 211, and the state in which the extension of 180 degrees is given around the central axis of the holding groove 211 is the shape that can maximize the resultant force.

  On the other hand, the pressing member 230 needs to be incorporated into the inner holding groove 211 via the opening provided in the cam follower main body 210. Therefore, it is necessary to set the optimal length of the spring receiving portion 232 in consideration of the required magnitude of the resultant force and the size of the opening of the cam follower main body 210.

  FIG. 3B is a schematic view for explaining the relationship between the cam follower 200 having the above-described biasing structure and the cam groove 121 with which the cam follower 200 is engaged. As shown in the drawing, the pressing member 230 of the cam follower 200 is in contact with one wall surface of the cam groove 121, and the resultant force of the biasing force acts on this side surface. By the reaction force of the resultant force, the cam follower 200 is always urged to the other wall surface, so that the generation of backlash between the cam follower 200 and the cam groove 121 is prevented.

  Here, the protrusion 231 of the pressing member 230 is focused. The contact surface of the projecting portion 231 in contact with the side wall of the cam groove 121 is substantially the same as the side surface of the cam follower main body 210, as can be seen from FIG. With such a curved surface shape, the angle range in which biasing can be appropriately performed can be widened even when the inclination angle of the engaged cam groove with respect to the optical axis changes, as compared with the case where the contact surface is on a plane. Is possible. Also, a flat surface may be adopted as the contact surface.

  In the present embodiment, as can be understood from FIG. 2A, the biasing mechanism is provided only at the upper portion of the cam follower 200. That is, the biasing mechanism is configured to correspond to the cam groove 121 of the cam barrel 120. And the biasing mechanism corresponding to the rectilinear guide groove 111 of the fixed cylinder 110 is not provided.

  Next, the holding of the coil spring 220 in the cam follower main body 210 will be described. FIG. 4 is a cross-sectional view for explaining the cam follower 200 before the pressing member 230 is assembled. Since there is no pressing member 230 for compressing the coil spring 220, the coil spring 220 shown in this figure is in a natural length state.

  As also shown in FIG. 2A, the coil spring 220 is held by a holding groove 211 provided on the inner peripheral side of the cam follower main body 210. The holding groove 211 is a groove formed such that the inner diameter on the inner peripheral side of the cam follower main body 210 is increased by one step, and has a size such that the coiled spring 220 accommodated does not interfere with the screw 240. The coil spring 220 is held along the holding groove 211.

  The coil spring 220 is held in the holding groove 211 by an elastic force that acts to return the spring of the coil spring straight. Therefore, the coil spring 220 does not fall off the cam follower main body 210 even when the pressing member 230 is not incorporated in the state of this figure. Therefore, storage and handling of the cam follower 200 in the unit state in the assembly process become very easy.

  Further examination of storage and handling in the unit state shows that the performance is further improved if the pressing member 230 is incorporated. For example, in the state where only the coil spring 220 is incorporated, the possibility that the coil spring 220 may fall off from the hole through which the protrusion 231 of the pressing member 230 passes can not be denied. Then, by incorporating the pressing member 230, the through hole is closed, so that the coil spring 220 is more reliably prevented from falling off.

  That is, the cam follower 200 embodying the present invention can be stored and handled in a unit state incorporating the coil spring 220 and the pressing member 230 which are essential to the biasing mechanism. This means that it can be stored and handled in the same manner as a normal cam follower having no biasing mechanism, which is a great advantage.

  In the embodiment described above, the biasing mechanism of the present invention is provided only at the upper portion of the cam follower 200. However, the site for providing the biasing mechanism is not limited to this. The biasing mechanism may be provided only on the lower portion of the cam follower 200.

  Further, as shown in the perspective view of FIG. 5, it is also possible to provide a biasing mechanism on either the upper or lower end. In this case, with the configuration of the embodiment described above, it is possible to perform rattling on any of the cam groove 121 and the rectilinear guide groove 111 with which the cam follower 200 is engaged, so a very high effect is expected. Be

  As described above, according to the cam follower described in the present invention and the lens barrel having the same, the coil spring is disposed in the circumferential direction of the central axis of the cam follower, and the pressing portion Since the inner wall of the groove is pressed, generation of rattling of the cam follower can be effectively prevented while having a simple configuration. In addition, since the coil spring does not drop out of the holding portion due to its own elastic force, storage and handling in a unit state incorporating the coil spring become easy.

Reference Signs List 100 lens barrel, 110 fixed barrel, 111 linear guide groove, 120 cam barrel, 121 cam groove, 130 linear barrel, 140 focus operation ring, 151 first group moving frame, 152 second group moving frame, 200 cam follower, 210 cam follower main body, 211 holding groove, 220 coil spring, 230 pressing member, 231 projecting portion, 232 spring receiving portion, 240 screw

Claims (4)

A cam follower body engaged with the at least one groove;
A coil spring held by a holding portion provided circumferentially with respect to the central axis of the cam follower main body;
A pressing member which protrudes from a hole provided on the side surface of the cam follower main body and which elastically contacts one wall surface of the groove by the biasing force of the coil spring;
The cam follower characterized by having. The pressing member has a projecting portion projecting through the hole and a spring receiving portion in pressing contact with both ends of the coil spring, and elastically compresses the coil spring in a direction along the holding portion, and the spring compresses by the elastic compression. 2. The cam follower according to claim 1, wherein a resultant force in the projecting direction of the protrusion among the urging forces generated in the receiving portion is the urging force of the pressing member. The cam follower is engaged with the two groove portions adjacent in the central axis direction, and an urging mechanism including the coil spring and the pressing member is laminated in the central axis direction so as to correspond to the respective groove portions. The cam follower according to claim 1 or 2, comprising.   A lens barrel comprising the cam follower according to any one of claims 1 to 3.

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